In recent years, single-lens reflex digital cameras capable of recording an image of higher image quality than compact digital cameras have been widespread.
Patent document 1 discloses configuration of such single-lens reflex digital camera. In a body of the single-lens reflex camera disclosed in the Patent document 1, a lens mount, a mirror box, a shutter device and an imaging sensor are arranged along an optical axis in this order. The mirror box has a movable mirror for guiding light incident through a lens to a prism and an optical finder while photographing is not performed. When the user presses a release button, the movable mirror rotates and withdraws from the optical axis and the light incident through the lens enters the imaging sensor. The imaging sensor converts the incident light into an electrical signal and outputs the electrical signal. The outputted electrical signal is sent to a signal processing circuit to generate an image signal.